Atherosclerosis MCQ — NEET PG Practice Question | NEETPGAI
Atherosclerosis
medium
microscope Pathology
A 58-year-old man from Delhi presents to the emergency department with acute onset chest pain radiating to the left arm for 2 hours. He has a 15-year history of hypertension and type 2 diabetes mellitus, both poorly controlled. On examination, blood pressure is 165/95 mmHg, heart rate 102/min. ECG shows ST elevation in leads II, III, and aVF. Coronary angiography reveals a thrombotic occlusion of the right coronary artery with atherosclerotic plaque. Which of the following histological features is most characteristic of the atherosclerotic plaque that precipitated this acute coronary syndrome?
A. Homogeneous calcification throughout the plaque with minimal cellular infiltration
B. Predominantly hyaline material with fibrin deposition and neutrophilic infiltration
C. Thick fibrous cap with sparse lipid accumulation and predominant smooth muscle cells
D. Lipid-rich core with thin fibrous cap and abundant macrophage-derived foam cells
Explanation
Pathological Features of Vulnerable Atherosclerotic Plaques
Histology of Plaque Prone to Rupture
Key Point
Acute coronary syndromes are typically triggered by rupture of a vulnerable (unstable) plaque, not a stable, calcified one. The characteristic features of such plaques are:
1.
Lipid-rich necrotic core — composed of cholesterol, cholesterol esters, and cellular debris
2.
Thin fibrous cap — often <65 μm thick, composed of smooth muscle cells and collagen
3.
Abundant inflammatory infiltrate — macrophage-derived foam cells, T lymphocytes, and mast cells
4.
Neovascularization — immature vessels prone to hemorrhage
5.
Reduced smooth muscle cells — due to apoptosis and loss of structural support
Why This Plaque Type Causes ACS
The thin fibrous cap is mechanically weak and prone to rupture under hemodynamic stress (especially in hypertensive patients). Rupture exposes the thrombogenic lipid core to blood, triggering platelet aggregation and thrombus formation — leading to acute occlusion and myocardial infarction.
High-YieldNEET PG
The lipid-rich, thin-capped plaque with foam cells is the hallmark of vulnerable plaque and is the morphological substrate of acute coronary syndromes. This is tested frequently in NEET PG pathology.
Comparison: Stable vs. Vulnerable Plaques
Table
Feature
Stable Plaque
Vulnerable Plaque
Fibrous cap
Thick (>65 μm)
Thin (<65 μm)
Lipid core
Small, sparse
Large, lipid-rich
Foam cells
Few
Abundant
Smooth muscle
Prominent
Sparse/apoptotic
Calcification
Extensive
Minimal
Risk of rupture
Low
High
Clinical presentation
Stable angina
ACS (MI, unstable angina)
Clinical Pearl
In this patient, the combination of poorly controlled hypertension and diabetes accelerates atherosclerotic plaque development and destabilization. The acute presentation with ST elevation and angiographic thrombus indicates acute plaque rupture with superimposed thrombosis.
